Two plates with area A are held a distance d apart and have a net charge +Q, and -Q, respectively. Assume that all the charge is uniformly distributed on the inner surfaces of the plates.

The left plate has charge -Q, the right plate has charge +Q, separated by distance d.

1) Find the charge density on the plates.
2) Find the electric potential difference between the plates.
3) Show that the capacitance of the enlarged plates in this case is the same as the capacitance in a case where